In the fields of high technology, heavy industrial and chemical processing, there exist a multitude of material handling problems. At times, some of these problems become so severe that they can shut down manufacturing components or entire units while the material handling units are cleaned. One such problem involves tank cleaning in a wide range of industries, such as, for example, pulp and paper industries, chemical industries, mining and refinery industries and steel industries. These problems exist when a liquid in a holding tank can no longer dissolve further solids, and the solids fall out or are precipitated and load the bottom of a holding or treating tank. Such fallout, in time, reduces tank capacity, stopping pumps, and, in some cases, locking in valuable capital cost of material.
A standard method of removing the built-up solids from the bottom of the tank has been to take the tank "off-line," i.e., no more liquid or solids are introduced into the tank, and the tank is disconnected from the plant which supplies it. When the tank is off-line, as much liquid as possible is removed from the tank. A hole is then cut into the side of the tank and a front-end loader, such as, for example, a Bobcat, or the like, is used to scoop out the built-up solids. The solids thus removed are loaded onto trucks or other suitable transport means and taken to landfills for disposal.
The standard removal method has many associated disadvantages. For example, the material removed from the tank is generally deposited in a landfill. Environmental concerns make landfilling the recovered solids increasingly undesirable. Additionally, by disposing of the built-up solids, there is no recovery of valuable material contained in the solids. Moreover, in the conventional method described above, the tank must be cut open to recover the built-up solid material. Therefore, the tank must be either repaired or replaced. Conventional tank-cleaning methods also involve disadvantages relating to cost and time. Another disadvantage associated with conventional tank-cleaning techniques is that operating any type of combustion engine in a closed tank environment poses significant safety risks.
Therefore, what is needed is a system for removing built-up solids from a tank bottom that does not require destruction of the tank, alleviates some of the environmental impact of depositing the removed solids in landfills and allows the safe reclamation of valuable products contained in the tank.